New research has found the first evidence that large rivers control desert sands and dust. But how exactly? First we need to know a little bit about loess.

ADVERTISEMENT

Loess is a silt-sized sediment which is formed by the accumulation of wind-blown dust. Loess deposits may be very thick and often blankets areas. One of the largest deposits of loess is in an area right-fully named the Loess Plateau, a 640,00 square kilometer area in the upper and middle China's Yellow River and China proper. However, there are also large loess deposits in the central United States and central Europe.

The origins of this loess-forming dust and its relationship to sand has previously been the subject of considerable debate. So to better study these origins, a team of researchers led by Royal Holloway University focused their efforts on northern China where loess deposits can be as deep as 300 feet.

Researchers first analyzed individual grains of fine wind-blown dust deposited in the Chinese Loess Plateau that has formed thick deposits over the past 2.5 million years. They also analyzed the Mu Us desert in Inner Mongolia and the Yellow River, one of the world's longest rivers, to identify links between the dust deposits and nearby deserts and rivers.

The results showed that the Yellow River transports large quantities of sediment from northern Tibet to the Mu Us desert and further suggests that the river contributes a significant volume of material to the Loess Plateau.

"The Yellow River drains the northeast Tibetan plateau and so the uplift of this region and the development of Yellow River drainage seems to control the large scale dust deposits and sand formation in this part of China," said lead researcher Tom Stevens from the Department of Geography at Royal Holloway.

"Identifying how this dust is formed and controlled is important, since it drives climate change and ocean productivity and impacts human health. Its relationship to the river and Tibet implies strong links between tectonics and climate change. This suggests that global climate change caused by atmospheric dust may be influenced by the uplift of Tibet and changes in major river systems that drain this area."

The research was published this week in the journal Quaternary Science Reviews.